Perhaps a bdr that would be interesting that would go clear across could include a gulf coast section all the way up to Port Arthur Texas. From San Antonio, trace the Guadalupe River via the lower mission valley road to port lavaca then up the coast road to Galveston and Ferry Crossing over to Port Arthur. Any way you cut across it, you are going to have to pound the pavement sometime and put up with the 99% private property. Would be an epic journey for sure. End with a crossing of this monster Start at el Paso, end in port Arthur. WOW!
Yes, the further east, we run into greater civilization and multi millions of humans.